The invention relates to a cryogenic device for medical applications. The invention more particularly relates to cryogenic device to be used once for ophthalmologic surgery.
In the prior art, cryogenic devices for medical applications are known. Such devices are more particularly used in the field of ophthalmologic cryosurgery and more particularly to treat retinal detachment by generating a cold point making it possible to create an adhesive scar by burning tissues between the retina and the choroid. The devices of the prior art are generally composed of a supply conduit connected to a source of cryogenic gas (nitrous oxide, carbon dioxide), of a conduit for discharging said gas, of a metal tip intended to be brought into contact with the area to be cooled and provided with a gas release chamber and a gas injection nozzle which supplies the gas from the supply conduit to the release chamber.
Manufacturing the devices of the prior art is expensive, takes time and is difficult more particularly because of the number of parts which compose the same. Consequently, in order to limit the costs, the devices are generally intended to be used many times. This imposes that such devices are capable of supporting sterilisation conditions at the hospital or according to international standards, sterilisation is obtained by staying in an autoclave at 125° C. for 10 minutes. Because the French standard is still more restricting since it requires a 20 minutes' stay at 134° C. Such constraints imply technological choices which make the devices still more complex and more expensive. In addition, sterilised devices using this procedure undergo deteriorations imposing frequent and costly maintenance actions when and as they are sterilised.
In order to remedy such drawbacks, the invention aims at providing a cryogenic device to be used once which can be reliable and the manufacturing of which is simple and less expensive. Another object of the invention is also to provide a light ergonomic, sterile and secured cryogenic device.
For this purpose and according to a first aspect, the invention provides a cryogenic device for surgical use making it possible to cool an area of the body including:                an end piece including a metal tip intended to be brought into contact with the area to be cooled and a gas release chamber;        a conduit for supplying the chamber with cryogenic gas; and        a conduit for discharging the cryogenic gas from the chamber; the supply conduit and the discharge conduit being formed in a common flexible extruded tube, one end of which is inserted into the end piece.Then, the number of parts composing the device is limited. In addition, the mounting operations are simplified, since the tube containing both supply and discharge conduits is directly inserted into the end piece.        
Advantageously, the end piece is made integral with one end of the flexible tube using gluing means. Then, the number of parts is limited by the utilisation of glue and the mounting is particularly simple. Of course using glue is possible only if the probe is sterilised at a low temperature. In practice, low temperature sterilisation, for example using 45° ethylene oxide, requires extractors which are not available in hospitals and it is thus mainly performed under industrial conditions. As a matter of fact, an attachment using a simple gluing step can be considered only because the mounting of the device is much simplified by the utilisation of a two-conduit unique tube; and thus the manufacturing cost can be globally reduced so much so that a one-time use is economically justified.
In one embodiment, the free end of the flexible tube inserted into the end piece is threaded so as to create a roughness at the gluing interface between the end piece and the flexible tube. Advantageously, the supply conduit has a section which is smaller that of the discharge conduit. In one embodiment, the supply conduit has substantially the shape of a crescent and the end of the support conduit is bevelled. Advantageously, the injection nozzle is inserted into the supply conduit. Preferably, the injection nozzle has a conical injection tip.
In one embodiment of the invention, the cryogenic device includes a nut provided with an internal thread and an external thread, a handle provided with the thread cooperating with the external thread of the nut, the end of the flexible tube being provided with a thread cooperating with the internal thread of the nut. Advantageously, the cryogenic device includes an isolating sleeve covering a portion of the end piece. In practice, the supply conduit is connected to a source of pressurised cryogenic gas. The discharge conduit is connected to a silencer discharging gas towards the outside.